High capacity solid filtration media

ABSTRACT

A high capacity filtration media, method of preparing the media, and method of treating a fluid stream with the media are provided. The media contain a porous substrate impregnated with high concentrations of a permanganate. Preferably, the media includes a porous substrate impregnated with at least about 8% permanganate by weight. The media can optionally contain sodium bicarbonate. Improved capacity for the removal of undesirable compounds such as ethylene, formaldehyde, hydrogen sulfide and methyl mercaptan are achieved.

TECHNICAL FIELD

The present invention relates generally to a composition and method forthe removal of compounds having disagreeable odors, toxic properties orcorrosive properties from gaseous streams. The invention moreparticularly relates to the use in filter beds of a high capacity solidfiltration media containing a substrate impregnated with a permanganate.

BACKGROUND OF THE INVENTION

The removal of toxic, corrosive and odorous gases can be accomplished bya number of techniques. These may include wet scrubbing, incineration,and removal via gas-phase air filtration using a variety of dryscrubbing adsorptive, absorptive, and/or chemically impregnated media.As opposed to these other methods, gas-phase air filtration does notrequire the consumption of large quantities water or fuel. Dry-scrubbingmedia can be engineered from a number of common adsorbent materials withor without chemical additives for the control of a broad spectrum ofgases or tailored for specific gases.

In contrast to the reversible process of physical adsorption, chemicaladsorption, also referred to as chemisorption, is the result of chemicalreactions on the surface of the media. This process is specific anddepends on the physical and chemical nature of both the media and thegases to be removed. Some oxidation reactions can occur spontaneously onthe surface of the adsorbent, however, a chemical impregnant is usuallyadded to the media. The impregnant imparts a higher contaminant removalcapacity and can lend some degree of specificity. Although someselectivity is apparent in physical adsorption, it can usually be tracedto purely physical, rather than chemical, properties. In chemisorption,stronger molecular forces are involved, and the process is generallyinstantaneous and irreversible.

Undesirable airborne compounds, including sulfur compounds, such ashydrogen sulfide and dimethyl sulfide, ammonia, chlorine, formaldehyde,urea, carbon monoxide, oxides of nitrogen, mercaptans, amines, isopropylalcohol and ethylene, occur in a number of environments, where most areprimarily responsible for the presence of disagreeable odors, orirritating or toxic gases. Such environments include petroleum treatmentand storage areas, sewage treatment facilities, hospitals, morgues,anatomy laboratories, animal rooms, and pulp and paper production sites,among others. These undesirable compounds may be bacterial breakdownproducts of higher organic compounds, or simply byproducts of industrialprocesses.

Hydrogen sulfide (“H₂S”), a colorless, toxic gas with a characteristicodor of rotten eggs, is produced in coal pits, gas wells, sulfursprings, and from decaying organic matter containing sulfur. Controllingemissions of this gas, particularly from municipal sewage treatmentplants, has long been considered desirable. More recently, protectingelectronic apparatus from the corrosive fumes of these compounds hasbecome increasingly important. Furthermore, H₂S is flammable.

Ammonia (“NH₃”) is also a colorless gas. It possesses a distinctive,pungent odor and is a corrosive, alkaline gas. The gas is produced inanimal rooms and nurseries, and its control also has long beenconsidered important.

Chlorine (“Cl₂”) is a greenish-yellow gas with a suffocating odor. Thecompound is used for bleaching fabrics, purifying water, treating iron,and other uses.

Control of this powerful irritant is necessary for the well-being ofthose who work with it or are otherwise exposed to it. At lower levels,in combination with moisture, chlorine has a corrosive effect onelectronic circuitry, stainless steel and the like.

Formaldehyde (“OCH₂”) is a colorless gas with a pungent, suffocatingodor. It is present in morgues and anatomy laboratories, and because itis intensely irritating to mucous membranes, its control is necessary.

Urea (“OC(NH₂)₂”) is present in toilet exhaust and is used extensivelyin the paper industry to soften cellulose. Its odor makes control ofthis compound important.

Carbon monoxide (“CO”), an odorless, colorless, toxic gas, is present incompressed breathing air. Oxygenation requirements for certainatmospheres, including those inhabited by humans, mandate its control.

Oxides of nitrogen, including nitrogen dioxide (“NO₂”), nitric oxide(“NO”), and nitrous oxide (“N₂O”), are compounds with differingcharacteristics and levels of danger to humans, with nitrous oxide beingthe least irritating oxide. Nitrogen dioxide, however, is a deadlypoison. Control of pollution resulting from any of these oxides isdesirable or necessary, depending on the oxide.

Mercaptans and amines, including methyl mercaptan (“CH₃SH”), butylmercaptan (“C₄H₉SH”) and methyl amine (“CH₃NH₂”), are undesirable gasespresent in sewerage odor. The control of these gases is desired for odorcontrol.

Isopropyl alcohol (“(CH₃)₂CHOH”) is a flammable liquid and vapor.Inhalation of the vapor is known to irritate the respiratory tract.Furthermore, exposure to high concentrations of isopropyl alcohol canhave a narcotic effect, producing symptoms of dizziness, drowsiness,headache, staggering, unconsciousness and possibly death. The control ofthis vapor in print processing and industrial synthesis is desired.

Ethylene (“C₂H₄”) is a colorless, flammable gas. It is a simpleasphyxiant that accelerates the maturation or decomposition of fruits,vegetables, and flowers. Control of this compound prolongs themarketable life of such items.

The airborne compounds described above can have a detrimental effect onthe local environment. For example, acidification is caused by emissionsof sulfur dioxide and nitrogen compounds (nitrogen oxides and ammonia),which in turn cause acid rain. Furthermore, nitrogen oxides and volatileorganic compounds from vehicular traffic, electricity and heatproduction, as well as from industrial facilities may, under certainconditions, contribute to the formation of photochemical oxidants, amongwhich ozone is the dominating substance. Ozone is a colorless gas thatforms when nitrogen oxides mix with hydrocarbons in the presence ofsunlight. In addition to causing environmental damage, ozone poses ahealth hazard, particularly for children, the elderly and individualswith asthma or lung disease.

Attempts have been made to provide solid filtration media for removingthe undesirable compounds described above from fluid, or moving,streams, such as gas or vapor streams. Desired features of such mediaare a high total capacity for the removal of the targeted compound sothat the media lasts longer and need not be replaced frequently, a highefficiency in removing the compound from an air stream contacting themedia so that the compound is removed quickly, and a high ignitiontemperature (non-flammability). High capacity and high efficiency are,in turn, directly affected by the porosity and pore structure of thesolid filtration media, while the capacity, efficiency and ignitiontemperature are all affected by the specific composition of the media.

Although a variety of permanganate-impregnated substrates are known forremoving undesirable contaminants from fluid streams, these knownimpregnated substrates all demonstrate a limited capacity and,therefore, a low efficiency for the removal of undesirable compoundsfrom the streams. These limitations arise to a large extent from aninsufficient porosity of the solid filtration media or a clogging ofpores with byproducts formed by reactions of the impregnate with thecontaminant. This results in the currently available media not meetingthe needs of various industries.

Therefore, what is needed is a high efficiency, high capacity, lowflammability permanganate-impregnated substrate for the removal ofundesirable compounds from gas streams. Such an impregnated substrateneeds to be long-lasting, requiring fewer replacements and therebyminimizing replacement and maintenance costs. Also needed is a highcapacity impregnated substrate that may be used in small filter beds,and therefore may allow the treatment of fluid streams where there aresignificant space limitations.

SUMMARY OF THE INVENTION

High capacity solid filtration media, methods of preparing the same andmethods of treating a fluid stream with the solid filtration media areprovided. The solid filtration media described herein are useful forremoving or reducing undesirable contaminants from a gaseous fluidstream.

Generally described, the high capacity solid filtration media include aporous, impregnated substrate having high levels of impregnate. Theimpregnate is a permanganate, preferably a permanganate salt having highwater solubility, such as sodium permanganate or lithium permanganate. Agas-evolving or gas-producing material such as sodium bicarbonate mayalso be included in the media. In contrast to presently availablefiltration media, the high capacity solid filtration media describedherein contain levels of permanganate approximately 8% or higher,thereby providing an increased efficiency for removing undesirablegaseous compounds from a fluid stream, particularly compounds such asethylene, formaldehyde and methyl mercaptan from gaseous streams byexhibiting a higher capacity for contaminant. For example, when used toremove ethylene from a gaseous stream, the media described hereinutilizing sodium permanganate have an ethylene capacity of approximately9%, whereas currently available potassium permanganate-impregnated mediaexhibit a maximum ethylene capacity of only approximately 3%.

The present invention addresses an existing need in the industry byproviding a high capacity, low flammability permanganate-impregnatedsubstrate for the removal of undesirable contaminants from gas streams.The permanganate-impregnated substrate provides a long lastingfiltration media that can be replaced less frequently, therebyminimizing maintenance and replacement costs. Due to its high capacity,the impregnated substrate described herein may be used in small filterbeds, thereby allowing the treatment of fluid streams where significantspace limitations exist. The filtration media described herein yield anequivalent or superior capacity over activated carbon adsorbents and aremuch less expensive and considerably less flammable than activatedcarbon adsorbents.

Generally described, the filtration media contain at least approximately8% by weight of media composition of a permanganate, wherein thepermanganate has a higher solubility in water than that of potassiumpermanganate, and a porous substrate, wherein the permanganateimpregnates the porous substrate. The composition typically alsocontains at least approximately 5% water by weight of media composition.Preferably, the permanganate is a highly water soluble permanganate saltsuch as sodium permanganate or lithium permanganate. The poroussubstrate is typically selected from, but not limited to, activatedalumina, silica gel, a zeolite, adsorbent clay, kaolin, activatedbauxite, or combinations thereof, the preferred porous substrate beingalumina or an alumina-zeolite mix.

Preferred solid filtration media contain from approximately 8 toapproximately 25% permanganate, between approximately 5 and 25% water,and a porous substrate. More preferred solid filtration media containfrom approximately 15 to approximately 20% permanganate, betweenapproximately 5 and 25% water, and a porous substrate. Most preferably,the solid filtration media contain from approximately 18 toapproximately 19% permanganate, between approximately 5 and 25% water,and a porous substrate. All of the above percentages are by weight ofthe entire composition and, as described above, the permanganate has ahigher solubility in water than that of potassium permanganate.

In another embodiment, the media further contain a gas-evolvingmaterial, such as a carbonate compound, a bicarbonate compound, or acombination thereof, that function by producing a gas (typically CO₂)upon heating. For example, when the composition further contains sodiumbicarbonate, the sodium bicarbonate is present between approximately 5to 25%, and preferably is between about 15 to 20% by weight of theentire composition.

The high capacity solid filtration media composition described above areproduced by mixing water, a permanganate, and a substrate, and thenforming the mixture into at least one cohesive porous unit. The unit isthen cured at a temperature of from about 100° F. to about 200° F.,until the concentration of water is at least about 5% by weight of thecomposition, and the concentration of the permanganate is at least about8% by weight of the composition.

In accordance with a preferred method of making the solid filtrationmedia, an aqueous solution containing the permanganate is sprayed ontothe porous substrate. In an alternative aspect, water is combined with adry mixture containing the permanganate and the substrate. In yetanother aspect, an aqueous solution containing the permanganate issprayed onto a dry mixture containing the permanganate and thesubstrate. Optionally, sodium bicarbonate may be added either to the drymixture, to the water, or to both in the method of preparing thefiltration media.

Preferably, the unit formed as described above is cured until theconcentration of water is from about 5 to about 25% by weight of thecomposition, and the concentration of the permanganate is from about 8to about 25% by weight of the composition. Preferably, where sodiumbicarbonate has been added to the composition, the unit formed is cureduntil the concentration of sodium bicarbonate is between 15 to 20% byweight. More preferably, the unit is cured until the concentration ofthe permanganate is from about 15 to about 20% by weight of thecomposition. Most preferably, the unit is cured until the concentrationof the permanganate is from about 18 to about 19% by weight of thecomposition.

Yet another aspect of the present invention is a method of treating acontaminated fluid stream with the high capacity solid filtration mediadescribed herein. This method comprises contacting the contaminatedfluid stream with the solid filtration media to remove contaminant.

The high capacity filtration media, the method of preparation, and themethod of use provide improved efficiency and capacity in removingcontaminants, particularly odor-causing contaminants, from gas streams.

Accordingly, it is an object of the present invention to provide a highcapacity solid filtration media that efficiently removes undesirablecompounds from an air stream to reduce odors, minimize the corrosion ofmetals or electronics, and to provide a nontoxic or nonirritatingbreathing environment for humans and animals.

It is another object of the present invention to provide a high capacitysolid filtration media that is long-lasting and requires minimalmaintenance or replacement.

It is yet another object of the present invention to provide a solidfiltration media having a high ignition temperature, and therefore,limited flammability.

It is also an object of the present invention to provide an improvedsolid filtration media that is inexpensive to manufacture and use.

It is another object of the present invention to provide a solidfiltration media having such a high capacity for removing undesirablecompounds that less media needs to be utilized, therefore allowing theuse of smaller air filtration units.

It is yet another object of the present invention to provide a simple,inexpensive method of making an improved solid filtration media having ahigh efficiency and a high total capacity for the removal of anundesirable compound.

It is a further object to provide a rapid, efficient and inexpensivemethod of treating a contaminated air or gas stream with a solidfiltration media.

These and other objects, features and advantages of the presentinvention will become apparent after a review of the following detaileddescription of the disclosed embodiments and the appended claims.

DETAILED DESCRIPTION

High capacity solid filtration media, methods of preparing the same, andmethods of treating a fluid stream with the solid filtration media areprovided. The solid filtration media can be used to remove or reduceundesirable compounds, or contaminants, from a gaseous fluid stream. Thesolid filtration media contain permanganate and a porous substrate.Typically, the media also contain water. A gas-evolving material such assodium bicarbonate may also be included. In some embodiments, at leastone zeolite is optionally included in the media. The media containsignificantly higher levels of permanganate than previously believed tobe possible.

Generally described, the filtration media contain a substrateimpregnated with high levels of permanganate. The permanganate is ahighly water soluble permanganate having a solubility in water greaterthan that of potassium permanganate. The filtration media include atleast about 8% permanganate by weight of the composition. Thepermanganate is preferably a permanganate salt such as, but not limitedto, sodium permanganate (“NaMnO₄”), magnesium permanganate(“Mg(MnO₄)₂”), calcium permanganate (“Ca(MnO₄)₂”), barium permanganate(“Ba(MnO₄)₂”), and lithium permanganate (“LiMnO₄”). More preferably, thepermanganate salt is sodium permanganate (commercially available fromchemical suppliers such as Carus Chemical Co., Peru, Ill.) or lithiumpermanganate. Most preferably, the permanganate is sodium permanganatedue to its inexpensive commercial availability. The concentration of thepermanganate in the media is typically from about 8 to about 25%, morepreferably from approximately 15 to approximately 20%, and mostpreferably from approximately 18 to approximately 19%, by weight of thecomposition.

The porous substrate may be selected from the group consisting of, butnot limited to, activated alumina (Al₂O₃) (UOP Chemical, Baton Rouge,La.), silica gels (J. M. Huber, Chemical Division, Havre De Grace, Md.),zeolites (Steel Head Specialty Minerals, Spokane, Wash.), kaolin(Englehard Corp., Edison, N.J.), adsorbent clays (Englehard Corp.,Edison, N.J.), and activated bauxite. A preferred porous substrate isalumina. Preferably, the concentration of substrate in the filtrationmedia is from about 40 to 80%, and most preferably is from about 60 to75% in the absence of sodium bicarbonate and from about 40 to 60% if themedia contain sodium bicarbonate.

Another preferred porous substrate is a combination of alumina and azeolite, in which up to about 50% by weight of the porous substratecombination is a zeolite. Though not intending to be bound by thisstatement, it is believed that zeolites further control the moisturecontent of the filtration media by attracting and holding water, whichfunctions to keep more of the impregnate in solution. This effect, inturn, is believed to enhance the high capacity and improved efficiencyof the filtration media. As used herein, the term zeolite includesnatural silicate zeolites, synthetic materials and phosphate mineralsthat have a zeolite-like structure. Examples of zeolites that can beused in this media include, but are not limited to, amicite (hydratedpotassium sodium aluminum silicate), analcime (hydrated sodium aluminumsilicate), pollucite (hydrated cesium sodium aluminum silicate),boggsite (hydrated calcium sodium aluminum silicate), chabazite(hydrated calcium aluminum silicate), edingtonite (hydrated bariumcalcium aluminum silicate), faujasite (hydrated sodium calcium magnesiumaluminum silicate), ferrierite (hydrated sodium potassium magnesiumcalcium aluminum silicate), gobbinsite (hydrated sodium potassiumcalcium aluminum silicate), harmotome (hydrated barium potassiumaluminum silicate), phillipsite (hydrated potassium sodium calciumaluminum silicate), clinoptilolite (hydrated sodium potassium calciumaluminum silicate), mordenite (hydrated sodium potassium calciumaluminum silicate), mesolite (hydrated sodium calcium aluminumsilicate), natrolite (hydrated sodium aluminum silicate), amicite(hydrated potassium sodium aluminum silicate), garronite (hydratedcalcium aluminum silicate), perlialite (hydrated potassium sodiumcalcium strontium aluminum silicate), barrerite (hydrated sodiumpotassium calcium aluminum silicate), stilbite (hydrated sodium calciumaluminum silicate), thomsonite (hydrated sodium calcium aluminumsilicate), and the like. Zeolites have many related phosphate andsilicate minerals with cage-like framework structures or with similarproperties as zeolites, which may also be used in place of, or alongwith, zeolites. These zeolite-like minerals include minerals such askehoeite, pahasapaite, tiptopite, hsianghualite, lovdarite, viseite,partheite, prehnite, roggianite, apophyllite, gyrolite, maricopaite,okenite, tacharanite, tobermorite, and the like.

The concentration of water in the filtration media is typically at leastapproximately 5 to 25%, preferably from approximately 10 to 25%. One ofordinary skill in the art will understand that the concentration of freewater in the filtration media may be altered by the conditions present,such as the humidity and the temperature, during its storage and use.

Preferably, the solid filtration media includes from approximately 8 to25% permanganate, from about 5 to 25% water, and from approximately 40to 80% substrate, by weight of the composition. More preferably, themedia contain from approximately 15 to 20% permanganate, fromapproximately 5 to 25% water, and from approximately 40 to 80%substrate, by weight. Most preferably, the solid filtration mediacontain from approximately 18 to 19% permanganate, from approximately 10to 25% water, and from approximately 40 to 60% substrate, by weight. Asdescribed above, the permanganate is ideally sodium permanganate due toits high solubility in water and inexpensive commercial availability.

The gas-evolving material of the filtration media described herein is amaterial that produces or releases a gaseous substance upon heating, forexample during the curing step of forming the filtration media. Thebubbles formed in this heating process are instrumental in enhancing andcontrolling the pore structure of the filtration media. The gas-evolvingmaterial is usually selected from a carbonate compound, a bicarbonatecompound, or a combination thereof, that functions by producing carbondioxide gas upon heating. A preferred gas-evolving material is sodiumbicarbonate, because of its smooth release of carbon dioxide, and itsrelatively low cost. However, other bicarbonates and carbonates can beused in this media, the selection of which is understood by one ofordinary skill in the art. The number and size of the pores producedfrom heating the gas-evolving material is related to the concentrationof the gas-evolving material in the solid filtration media, thetemperature of curing, and the time of curing. Thus, increasing theconcentration of sodium bicarbonate in the composition increases thepore size and number, helps reduce and prevent clogging of the porestructure, enhances the retention of water, and sustains theconcentration of the permanganate in the filtration media.

In a preferred embodiment, the filtration media composition includes apermanganate, water, a substrate and sodium bicarbonate (“NaHCO₃”)(Rhone-Poulenc, Chicago Heights, Ill.), wherein the concentration ofsodium bicarbonate is from approximately 5 to 25%, and preferably from15 to 20%, by weight. In the embodiments where the filtration mediacontain sodium bicarbonate, the preferred concentration of alumina isfrom approximately 40 to 60%.

It is to be understood that, when referring to the relative weight ofcomponents, the water referred to in the present specification,examples, and tables is defined as the free water, and does not includethe bound water in the substrate. Free water is driven off by an oven atapproximately 200° F., but if left in the substrate it is available forthe oxidation reaction. In contrast, bound water is not driven out orevaporated except by a kiln at about 1800 to 2000° F., and the boundwater functions by holding the substrate together. Bound water is notavailable for reaction with the undesirable contaminants.

It is also to be understood that the term permanganate as usedquantitatively in the present specification, examples, and tablesrepresents the permanganate salt, not the permanganate ion, MnO₄ ⁻.Therefore, the percent ranges of permanganates in compositions in thepresent specification denote the percent of the permanganate salt in thecomposition, not the percent of the permanganate ion in the composition.

Terms such as “filtration media”, “adsorbent composition,” “chemisorbentcomposition,” and “impregnated substrate” are all interchangeable, anddenote a substance that is capable of reducing or eliminating thepresence of unwanted contaminants in fluid streams by the contact ofsuch a substance with the fluid stream. It is to be understood that theterm “fluid” is defined as a liquid or gas capable of flowing, or movingin a particular direction, and includes gaseous, aqueous, organiccontaining, and inorganic containing fluids.

Solid Filtration Media Preparation Methods

Also provided is a method of preparing high capacity solid filtrationmedia. The method includes mixing water, a permanganate, an optionalgas-evolving material, and a porous substrate, and then forming themixture into at least one cohesive porous unit. The unit is thentypically cured at a temperature of from about 100° F. to about 200° F.,until the concentration of water is at least about 5% by weight of thecomposition, and the concentration of the permanganate is at least about8% by weight of the composition. The size and shape of the cohesiveporous unit is not critical. Any size and shape of a porous unit knownin the art to reduce or eliminate undesirable contaminants from fluidstreams when in contact with the unit may be used. Preferably, theporous unit is a nominal ⅛″ diameter round pellet.

The method provided herein preferably includes forming an aqueoussolution containing the permanganate and optional gas-evolving materialand then mixing the aqueous permanganate solution with the poroussubstrate. To dissolve and maintain the permanganate in solution, theaqueous solution should be heated to approximately 160° to 200° F., andpreferably to approximately 180° to 190° F.

In another embodiment, the method includes forming a dry mixturecontaining the permanganate and the porous substrate, and then addingwater to the dry mixture.

In yet another embodiment, the method includes forming a dry mixturecontaining the permanganate, the optional gas-evolving material, and theporous substrate; forming a separate aqueous solution containing thepermanganate and the optional gas-evolving material, and then mixing theaqueous solution with the dry mixture. Optionally, the gas-evolvingmaterial such as sodium bicarbonate may be added either to the drymixture, to the water, or to both in the above methods of preparing thefiltration media.

Preferably, the unit formed is cured until the concentration of water isfrom about 5 to about 25%, most preferably from about 10 to about 25% byweight of the composition; the concentration of the permanganate is atleast about 8 to about 25% by weight of the composition, more preferablyfrom about 15 to about 20%, and most preferably from about 18 to about19%; and the concentration of the gas-evolving material is from about 5to about 25% by weight of the composition, most preferably from about 15to 20% by weight of the composition, after curing. The presence of agas-evolving material such as sodium bicarbonate allows for a lowercuring temperature, such as about 130° to 140° F., in contrast to theconventional curing temperature of about 200° F.

The impregnation treatment of the activated starting material inaccordance with the present method has not been found to be criticalwith respect to the particular sequence in which the dry mix isimpregnated with moisture and impregnates. The above combinations may bemixed in any manner which effectively produces the desired filtrationmedia. Impregnation may be carried out simply by immersing and soakingthe solid combination in a volume of impregnate solution. Also, theimpregnate solution may be passed through the combination rather thanbeing used as a static immersion treatment. However, it has been foundthat a preferred method of impregnation is spray addition in which animpregnate solution is sprayed onto a dry combination being tumbled in amixer. This method of impregnation has been described in U.S. Pat. No.3,226,332, which is herein incorporated by reference in its entirety.Other methods of impregnating the combinations will suggest themselvesas equally appropriate, and these are included within the scope of thepresent method.

In one embodiment utilizing the above spray addition method, the aqueousimpregnate solution of permanganate is sprayed onto a dry combination ofgas-evolving material, such as sodium bicarbonate, and a poroussubstrate, such as activated alumina. For example, the dry combinationpreferably contains between approximately 80 to 85% activated aluminaand between approximately 15 to 20% of sodium bicarbonate.

The concentration of the permanganate may vary in the solution to besprayed onto the dry combination. For example, to produce a solidfiltration medium containing approximately 20% permanganate, an aqueoussolution containing approximately 40% of permanganate, at betweenapproximately 160° F. to 200° F., and preferably at about 180° F. to190° F. should be sprayed on the dry combination of gas-evolvingmaterial and porous substrate being tumbled in a mixer. Also, to producea solid filtration medium containing approximately 8-9% permanganate, asolution of approximately 18% permanganate at between approximately 160°F. to 200° F., and preferably at about 180° F. to 190° F. should besprayed on the dry combination of gas-evolving material and poroussubstrate being tumbled in a mixer. Any concentration of permanganate inthe aqueous solution which is effective to yield the compositiondescribed herein may be used. Further, where the permanganate is eitherin the dry feed mixture or in both the aqueous solution and the dry feedmixture, any concentration of permanganate in the dry mixture and/or theaqueous solution which is effective to produce the composition describedherein may be used. For example, the media may be used to fillperforated modules to be inserted into air ducts in a manner known inthe art.

Contaminant Removal Methods

Also provided is a method of treating a contaminated fluid stream usingthe high capacity solid filtration media described herein or produced bythe process described above. This method involves contacting thecontaminated fluid stream with the solid filtration composition providedherein. Typically, the undesired contaminants will be removed from air,especially from air admixed with effluent gas streams resulting frommunicipal waste treatment facilities, paper mills, petrochemicalrefining plants, morgues, hospitals, anatomy laboratories, and hotelfacilities, and so forth. Methods of treating gaseous or other fluidstreams are well known in the art. As the method of treating fluidstreams is not critical to the present invention, any method known inthe art of treating fluid streams with the media described herein may beused.

The composition described herein is useful for removing undesiredcontaminants from gaseous streams. Undesirable airborne compounds to beremoved using the high capacity filtration media include, but are notlimited to, sulfur compounds (such as hydrogen sulfide and dimethylsulfide), ammonia, chlorine, formaldehyde, urea, carbon monoxide, oxidesof nitrogen, mercaptans (such as methyl mercaptan), amines, isopropylalcohol and ethylene. Typically, contaminants to be removed by employingthe media described herein include, but are not limited to, ethylene,formaldehyde and methyl mercaptan The concentrations of undesirablecontaminants in the gaseous streams is not considered critical to theprocess of contaminant removal, nor is the physical and chemical makeupof the gas stream considered critical. Even concentrations of theseundesirable compounds in gas streams resulting in levels lower than oneppb of the compounds passing through a solid filtration media bed perminute may be removed.

However, it has been found that flow rates of the gas stream beingcontacted with the bed of filtration media affect the breakthroughcapacities of the media. The preferred flow rate is between 10 and 750ft/min, and most preferably is between 60 and 100 ft/min, flowingperpendicularly to the face of the bed.

While not intending to be bound by the following statement, it isbelieved that it may be necessary that certain oxidizing conditionsprevail while using the solid filtration media described herein. Theextent of oxidation may affect the degree of purification achieved.Preferably, oxygen is present in the gas stream being treated, at leastin small amounts. This oxygen content is readily found in the gasstream, if air constitutes a sufficient portion of the gas stream beingtreated. If oxygen is totally absent or present in insufficient amounts,oxygen may be independently introduced into the gas stream beingtreated. A number of factors affect the amount of oxygen, which may berequired for maximum removal of the contaminants in a gas stream inaccordance with the present method, including the concentration andabsolute amount of compounds being removed from the gas stream beingtreated.

With respect to the amount of compound removed, it is believed that thefollowing factors affect the process: the basic degree of attraction ofthe activated substrate for the compound; the pore structure and poresize distribution; the size of the substrate; the specific surface areaof the substrate as affected by the number and size of pores; thesurface characteristics of the substrate; the amount of permanganatepresent; the amount of gas-evolving material present in the composition,which affects the number, size, and perhaps structure of pores; and theamount of water present.

The filtration media provided herein is appropriately used alone infilter beds for the removal of undesirable compounds. It is alsoappropriate, however, to use the composition in conjunction with filterbeds containing other filtration media, and also in conjunction withmechanical or electrostatic filters. Any such additional filters may beplaced either upstream (before the media described herein with respectto the effluent gas being treated) or downstream.

The above invention significantly increases the efficiency and capacityof impregnated porous substrates (filtration media) to remove certainundesired compounds from gaseous streams over the capacity ofimpregnated substrates currently available. Therefore, the lifetime of aspecific quantity of the high capacity filtration media will be muchlonger than the same quantity of the currently available filtrationmedia.

The extension of the lifetime of the filtration products willsignificantly reduce the purchasing, servicing, and installation costsof consumers and businesses. Also, the enhanced efficiency of the mediaallows for a new line of products, which are compact versions ofcurrently available units, but have the same performance as the larger,currently available units. The capability of creating significantlysmaller filtration units is useful for providing efficacious airfiltration in space-limited quarters, which previously could not utilizethe larger, currently available units.

Also, the filtration media described herein is less expensive than otherfiltration media having a roughly equivalent capacity. For example, themedia of the present invention has a capacity equivalent or superior tothe contaminant capacity of activated carbon adsorbents, particularly inrespect to ethylene and formaldehyde contaminants. However, the mediaprovided herein is considerably less expensive than activated carbonadsorbents.

Further, the filtration media provided herein is safe as it is notflammable, in contrast to carbon-containing filtration products. Thischaracteristic of the presently provided filtration media is significantto industries that manufacture or process flammable, fume producingmaterials, such as the petroleum industry for example.

In the high capacity filtration media described herein, the use of ahighly water soluble permanganate, having a water solubility higher thanthat of potassium permanganate, allows for an increase in theconcentration of permanganate in the media. This increased concentrationof permanganate greatly increases the removal capacity of the media forcontaminants. When performing accelerated capacity tests as described inthe examples below, the filtration media is examined at 100% efficiencyuntil the efficiency drops to a pre-determined level, in this case 99.5%efficiency. Once this breakthrough is achieved the test is complete, andremoval capacity can then be calculated. The capacity level isinherently linked to efficiency, because it is determined in associationwith the time taken for the efficiency to drop to 99.5%. Currentlyavailable potassium permanganate impregnated alumina media has acapacity of approximately 3% for the removal of ethylene. In contrast,the high capacity filtration media described herein containingapproximately 60% activated alumina, approximately 15-20% water, and19-20% sodium permanganate, exhibited an ethylene capacity ofapproximately 9%. Capacity tests were performed by challenging a knownquantity of the selected solid filtration media with 1.0% (by volume)ethylene gas at a constant flow rate and monitoring the concentration ofethylene in the gas stream exiting the solid filtration media. Theaccelerated removal capacity test is fully described in U.S. Pat. No.6,004,522, which is herein incorporated by reference in its entirety.

The high capacity of the solid filtration media described herein is notlimited to the removal of ethylene from a gaseous stream. Indeed, highcapacity is similarly achieved for other gaseous contaminant such ashydrogen sulfide, formaldehyde and methyl mercaptan. The results ofthese investigations are presented in the Examples, below.

Although the precise mechanisms by which the high capacity mediaoperates are not understood or fully appreciated, and its scope is notbound by the following theory, it is believed that the oxidationreactions between the permanganate and the undesirable contaminantsoccur primarily near the surface of the filtration media, rather thandeep within its pores. Therefore the media most likely perform atoptimal levels when the oxidative capabilities of the surface arecontinually regenerated. It is believed that the oxidative capability ofthe surface of the media is regenerated by the flow or migration ofpermanganate from the center of the media to the surface of the mediawhile the products of the oxidation reactions flow or migrate from thesurface of the media to the center of the media. It is also believedthat the higher the concentration of permanganate at the surface of themedia, the higher the capacity and efficiency of the media.

Furthermore, the fluidity of the permanganate solution directly affectsthe flow and thus the quantity of the permanganate reaching the surfaceof the media. Therefore, the media work well when an elevatedconcentration of free water is maintained in the media so that thepermanganate solution maintains a high level of fluidity and readilyflows to the surface of the media thereby maximizing the efficiency andcapacity of the media. A liquid path thus should be established betweenthe interior of the pores and the surface of the media. In this regard,the improved pore structure provided by the addition of a gas-evolvingmaterial to the filtration media is believed to enhance the ready flowof permanganate solution. This is contrary to conventional theories,which teach a need for penetration of the gaseous contaminants into thepores of the substrate.

This theory, presented above, explains why the capacity and efficiencyof the traditional filtration media could not surpass the capacity andefficiency obtained at the potassium permanganate concentrations of4-5%. As stated above, previously, various attempts were made toimpregnate the media with higher quantities of potassium permanganate,however, the majority of the free water has always been removed fromthese media. The efficiency and capacity of these highly impregnatedpotassium permanganate media remained constant or decreased relative tothe capacity achieved by media impregnated with 4-5% permanganate. Thereare three reasons for the failure of the highly impregnated mediacurrently available to obtain higher results. First, the highconcentration of permanganate and the low concentration of water causesthe permanganate to crystallize and clog the pores of the substratethereby blocking the flow of permanganate to the surface of the media.Second, the crystallized permanganate remains in the center of the mediaand therefore cannot move to the surface of the media to oxidizecontaminants. Third, it is difficult for any permanganate that may be insolution to move to the surface of the media as the permanganatesolution is very concentrated and has a low level of fluidity. It is forthese reasons that maintaining an elevated level of water in the mediais believed to be useful for improved filtration media, and is includedin the present invention. It is also believed that the unprecedentedimprovement in solid filtration media of this invention is due to recentadvances in the preparation and supply of commercially availablepermanganates. Historically these permanganates are supplied either asgranular crystals or relatively low aqueous concentrations. Potassiumpermanganate is known to crystallize in high concentration, asfrequently demonstrated in the literature. Concentrated aqueouspotassium permanganate (20%) can also precipitate during curing, andultimately clog the pores of filtration media. However, a permanganatehaving a water solubility greater than that of potassium permanganate,such as sodium permanganate, is miscible in water in all proportions (bycomparison, potassium permanganate solubility is approximately 6.5 g/100ml by weight, at 20° C.). Due in part to the important difference insolubility, it is now possible to incorporate substantially higherconcentrations (>20%) of permanganates, such as sodium permanganate,than previously obtained, ultimately yielding an increased removalcapacity of contaminates from gaseous streams. Furthermore, thesignificant increase in removal capacity of ethylene contaminants is duein part to the increased concentration of permanganate, but also due tothe formation of relatively small non-volatile waste products (CO₂ andH₂O) which are released from the solid filtration media, effectivelyproviding additional active surface area for multiple reactions withother gaseous contaminants.

The following examples will serve better to illustrate the high capacityof the solid filtration media described herein for the removal ofcontaminants in gas streams. It should be noted that the continuous flowsystems described in several of the following examples all were operatedat a relative humidity of 40-50%.

EXAMPLE 1

Preparation of Filtration Media Containing 13% Sodium Permanganate

A sodium permanganate impregnated alumina composition is prepared asfollows.

A dried feed mix is prepared by combining, by weight, 80-85% alumina,and 15-20% sodium bicarbonate. The dry feed mixture is sprayed with aheated aqueous sodium permanganate solution at 180 to 190° F. whilebeing tumbled in a tumble mill. The resulting pellets are dried at 130to 140° F. until the pellets contain about 20 to 25% free water.

To prepare solid filtration media containing approximately 13% sodiumpermanganate by dry weight, the aqueous sodium permanganate solutionpreferably contains approximately 26% sodium permanganate by weight. Itis to be understood that the aqueous sodium permanganate solution issprayed onto the dry feed while the dry mix is rolled in the pelletizingdisk as described in U.S. Pat. No. 3,226,332, incorporated herein byreference.

EXAMPLE 2

Preparation of Filtration Media Containing 4-5% Potassium Permanganate

A 4-5% potassium permanganate impregnated alumina composition wasprepared as follows.

A dry feed mix, consisting of 100% alumina, was sprayed with a heatedaqueous potassium permanganate solution at 180 to 190° F. while thedried feed was tumbled in a tumble mill. The resulting pellets were thendried at 130 to 140° F. until the pellets contained about 20 to 25% freewater.

To prepare solid filtration media containing approximately 4-5%potassium permanganate by dry weight, the aqueous potassium permanganatesolution preferably contained approximately 10% potassium permanganateby weight. It is to be understood that the aqueous potassiumpermanganate solution was sprayed onto the dry feed while the dry mixwas rolled in the pelletizing disk as described in U.S. Pat. No.3,226,332.

EXAMPLE 3

Preparation of Filtration Media Containing 19-20% Sodium Permanganate

A 19-20% sodium permanganate impregnated alumina composition wasprepared as follows.

A dried feed mix, consisting of 100% alumina, was sprayed with a heatedaqueous sodium permanganate solution at 180 to 190° F. while the driedfeed was being tumbled in a tumble mill. The resulting pellets were thendried at 130 to 140° F. in air until the pellets contained about 20 to25% free water.

To prepare a solid filtration media containing approximately 19-20%sodium permanganate, by dry weight, the aqueous solution preferablycontained approximately 40% sodium permanganate, by weight. It is to beunderstood that the aqueous potassium permanganate solution was sprayedon to the dry feed while the dry feed was rolled in the pelletizing diskas described in U.S. Pat. No. 3,226,332.

EXAMPLE 4

Preparation of Additional Permanganate-Impregnated Substrates

Using the methods described in Examples 2 and 3, above, the followingcompositions, by dry weight, were also prepared. TABLE I Composition ofSolid Filtration Media Sample Number Substrate % NaMnO₄ % KMnO₄ % H₂O 4AAlumina 4-5 0 15-20 4B Alumina 0 8-9 15-20 4C Alumina 8-9 0 15-20

The dry feed mix, consisting of 100% alumina, was mixed in a tumblingmill and sprayed with the appropriate amount of aqueous potassiumpermanganate or aqueous sodium permanganate solution, while tumbling, inthe manner described in U.S. Pat. No. 3,226,332. Curing was carried outas in Examples 2 or 3 to provide the cured pellets as a strong,non-dusting filter media suitable for placement in filter beds.

EXAMPLE 5

Standard Accelerated Test Method for Capacity Determination of Gas-PhaseAir Filtration Media.

The following accelerated test method is useful for determining thecapacity of removal of various gas-phase air filtration media whensubjected to a flowing gas stream containing high levels ofcontaminant(s). Low-level challenge testing of gas-phase air filtrationmedia, whether full-scale or small-scale, usually takes long periods oftime to obtain the desired results. The following method provides anaccelerated test for determining the removal capacities of various mediaby exposing them to high levels of contaminants.

The method is briefly summarized as follows: a known volume of media isplaced in an adsorption tube and exposed to a known concentration(usually 1% by volume) of contaminant gas(es) in a tempered, humidified,clean air system. The gas stream is calibrated to deliver a total flowrate of 1450±20 ml/min. The removal capacity is calculated as the amount(in grams) of contaminant removed from the air stream per volume (cubiccentimeters) of media at a 50 parts per million (“ppm”) breakthrough.

More specifically, the air utilized must be tempered, humidified, clean,oil-free, and compressed. Accordingly, the air must be passed through abed of activated carbon followed by a filter bed containing sodiumpermanganate impregnated alumina pellets. Each filter bed should containat least 300 ml (18.3 cu. in.) of media for each liter per minute (0.035cfm) of air flow. The media in each filter bed should be changed beforeeach test.

Media samples are preferably obtained from unopened originalmanufacturer's shipping or storage containers chosen at random wheneverpossible. The entire container, whenever possible or practical, shouldbe sampled by taking small amounts of media from throughout thecontainer and combining them into one larger sample.

The sample should be thoroughly mixed before being analyzed. Guidance onsampling may be obtained from ASTM Standard E300, entitled RecommendedPractice for Sampling Industrial Chemicals. If a test is to be runcomparing media of the same size or different sizes, the samplecollected may be screened through the appropriate sieves to sort themedia by size.

Using an appropriate sampling method, obtain a representative sample ofmedia (approximately 400 grams should be sufficient) and determine itsapparent density as per ASTM 2854, or an equivalent method. Obtain anadsorption tube which is a cylindrical tube where glass wool and/orbeads are optionally placed below the media, and the media and optionalglass wool or beads are supported by stainless steel mesh, a perforatedslotted glass disc, or a perforated slotted ceramic disc positionedbelow the media and glass wool or beads. After the adsorption tubehaving the glass wool or glass beads has been calibrated for the volumeof a known depth of media, weigh the adsorption tube to the nearest 1.0mg. Fill the adsorption tube to the desired depth via alternatelyfilling and gently tamping the tube to eliminate any dead space untilthe desired depth is reached. Weigh the filled adsorption tube to thenearest 1.0 mg.

The filled media tube is arranged such that a mixture of air andcontaminated gas enters the bottom of the tube, flows through the glasswool or beads, flows through the filtration media, and is then analyzedby a gas analyzer. Leaks in the gas system should be checked for andeliminated before beginning the analysis of the sample. Rotameters,analyzers, recorders, etc. should be calibrated over appropriate rangesaccording to the manufacturer's instructions or other standard methodssuch as ASTM Standard D3195, before any media is introduced into thesystem. Also, air and gas flow requirements should be determined andchecked against supply capabilities to assure proper air and gas flowsto the system.

Once the adsorption tube is in position, start the flow of the mixtureof contaminated gas and air and record the time, or time the test usinga stop watch. Continue the flow of the mixture of gas and air until abreakthrough of 50 ppm is observed or indicated by the gas analyzer.Record the time at breakthrough. It is preferable to use a gas analyzercapable of variable scale readouts to 50 ppm (±5 ppm), having specificor multiple gas capabilities.

The data obtained from the above analysis will yield the gas capacity ofthe media tested using the following equation:GAS CAPACITY (GM/CC)=(K×10⁻5)(C)(F)(t _(b))/Vwhere:

K=1.52 for H₂S, 2.86 for SO₂, 3.17 for Cl₂, 2.15 for CH₃SH, 0.76 forNH₃, 2.05 for NO₂, 1.16 for C₂H₄, 1.34 for OCH₂, and 1.39 for NO.

C=Concentration of challenge gas in air stream, Volume %.

F=Total stream flow rate, cc/min.

t_(b)=Time to 50 ppm breakthrough, minutes.

V=Volume of the adsorption tube media column, cc.

EXAMPLE 6

Capacity of Permanganate Impregnated Alumina Pellets in the Presence ofH₂S.

The results of tests comparing the capacities of various solidfiltration media are summarized in Table II below. The capacity testswere performed by challenging a known quantity of the selected solidfiltration media with 1.0% hydrogen sulfide gas at a constant flow rateand monitoring the concentration of hydrogen sulfide in the gas streamexiting the solid filtration media as described in Example 5. TABLE IIHydrogen Sulfide Capacity Tests for Various Media Media % KMnO₄ % NaMnO₄% H₂S capacity Example 2 4-5 0 8 Example 3 0 19-20 17 Sample 4A 0 4-5 8of Example 4 Sample 4B 8-9 0 16 of Example 4 Sample 4C 0 8-9 16 ofExample 4

EXAMPLE 7

Capacity of Permanganate Impregnated Alumina Pellets in the Presence ofEthylene.

The results of tests comparing the capacities of various solidfiltration media are summarized in Table III below. The capacity testswere performed by challenging a known quantity of the selected solidfiltration media with 1.0% ethylene gas at a constant flow rate andmonitoring the concentration of ethylene in the gas stream exiting thesolid filtration media as described in Example 5. TABLE III EthyleneCapacity Tests for Various Media Media % KMnO₄ % NaMnO₄ % Ethylenecapacity Example 2 4-5 0 2 Example 3 0 19-20 9 Sample 4A 0 4-5 2 ofExample 4 Sample 4B 8-9 0 3 of Example 4 Sample 4C 0 8-9 4 of Example 4

EXAMPLE 8

Capacity of Permanganate Impregnated Alumina Pellets in the Presence ofFormaldehyde.

The results of tests comparing the capacities of various solidfiltration media are summarized in Table IV below. The capacity testswere performed by challenging a known quantity of the selected solidfiltration media with 1.0% formaldehyde gas at a constant flow rate andmonitoring the concentration of formaldehyde in the gas stream exitingthe solid filtration media as described in Example 5. TABLE IVFormaldehyde Capacity Tests for Various Media Media % KMnO₄ % NaMnO₄ %formaldehyde capacity Example 2 4-5 0 2 Example 3 0 19-20 8 Sample 4A of0 4-5 2 Example 4 Sample 4B of 8-9 0 3 Example 4 Sample 4C of 0 8-9 4Example 4

EXAMPLE 9

Capacity of Permanganate Impregnated Alumina Pellets in the Presence ofMethyl Mercaptan.

The results of tests comparing the capacity of solid filtration media ofthe present invention are summarized in Table V below. The capacitytests were performed by challenging a known quantity of the selectedsolid filtration media with 1.0% methyl mercaptan gas at a constant flowrate and monitoring the concentration of methyl mercaptan in the gasstream exiting the solid filtration media as described in Example 5.TABLE V Methyl Mercaptan Capacity Tests for Various Media % MethylMercaptan Media % KMnO₄ % NaMnO₄ capacity Example 2 4-5 0 3 Example 3 019-20 11 Sample 4A of 0 4-5 3 Example 4 Sample 4B of 8-9 0 5 Example 4Sample 4C of 0 8-9 6 Example 4

It should be understood, of course, that the foregoing relates only tocertain embodiments of the present invention and that numerousmodifications or alterations may be made therein without departing fromthe spirit and the scope of the invention. All of the publications orpatents mentioned herein are hereby incorporated by reference in theirentireties.

1. A composition comprising a porous substrate impregnated with apermanganate, wherein the permanganate is a permanganate salt having asolubility in water greater than that of potassium permanganate, whereinthe concentration of permanganate salt in the composition is at leastapproximately 8% permanganate salt by weight.
 2. The composition ofclaim 1, wherein the permanganate salt is selected from the groupconsisting of sodium permanganate, magnesium permanganate, calciumpermanganate, barium permanganate, lithium permanganate, or acombination thereof.
 3. The composition of claim 1, wherein thecomposition comprises at least about 13 to about 25% permanganate saltby weight.
 4. The composition of claim 1, wherein the compositioncomprises at least about 15 to about 20% permanganate salt by weight. 5.The composition of claim 1, wherein the composition comprises at leastabout 18 to about 19% permanganate salt by weight.
 6. The composition ofclaim 1, wherein the composition further comprises t least about 5% andabout 25% water by weight.
 7. The composition of claim 1, wherein thepermanganate salt comprises odium permanganate.
 8. The composition ofclaim 1, further comprising a gas evolving material selected from acarbonate compound, a bicarbonate compound, or a combination thereof. 9.The composition of claim 1, wherein the porous substrate comprisesactivated alumina, a silica gel, a zeolite, a zeolite-like mineral,kaolin, an adsorbent clay, activated bauxite, or a combination thereof,and wherein the porous substrate is between about 40 and about 80% byweight of the composition.
 10. The composition of claim 9, wherein thezeolite or zeolite-like mineral is selected from amicite, analcime,pollucite, boggsite, chabazite, edingtonite, faujasite, ferrierite,gobbinsite, harmotome, phillipsite, clinoptilolite, mordenite, mesolite,natrolite, garronite, perlialite, barrerite, stilbite, thomsonite,kehoeite, pahasapaite, tiptopite, hsianghualite, lovdarite, viseite,partheite, prehnite, roggianite, apophyllite, gyrolite, maricopaite,okenite, tacharanite, tobermorite, or a combination thereof.
 11. Thecomposition of claim 8, wherein the gas-evolving material comprisessodium bicarbonate and the porous substrate comprises activated aluminaor a combination of activated alumina and at least one zeolite orzeolite-like mineral.
 12. The composition of claim 11, wherein theconcentration of sodium bicarbonate is between about 5 and about 25% byweight of the composition.
 13. A method of treating a contaminated fluidstream comprising contacting the contaminated fluid stream with a solidfiltration composition such that contaminants are removed from the fluidstream, wherein the solid filtration composition comprises a poroussubstrate impregnated with a permanganate, wherein the permanganate is apermanganate salt having a solubility in water greater than that ofpotassium permanganate, wherein the concentration of permanganate saltin the composition is at least approximately 8% permanganate salt byweight.
 14. The method of claim 13, wherein the concentration ofpermanganate is between about 13 and about 25% by weight of thecomposition.
 15. The method of claim 13, wherein the concentration ofpermanganate is between about 15 and about 20% by weight of thecomposition.
 16. The method of claim 13, wherein the concentration ofpermanganate is between about 18 and about 19% by weight of thecomposition.
 17. The method of claim 13, wherein the composition furthercomprises a gas-evolving material having a concentration between about 5and about 25% by weight of the composition.
 18. The method of claim 13,wherein the contaminated fluid stream contains hydrogen sulfide and theremoval capacity of the solid filtration unit is at least about 16% 19.The method of claim 13, wherein the contaminated fluid stream containsethylene and the removal capacity of the solid filtration unit is atleast about 4%
 20. The method of claim 13, wherein the contaminatedfluid stream contains formaldehyde and the removal capacity of the solidfiltration unit is at least about 4%
 21. The method of claim 13, whereinthe contaminated fluid stream contains methyl mercaptan and the removalcapacity of the solid filtration unit is at least about 6%
 22. A methodof preparing a solid filtration composition comprising: a) mixing apermanganate and a porous substrate, wherein the permanganate is apermanganate salt having a solubility in water greater than that ofpotassium permanganate; b) spraying the mixture with water; c) formingthe mixture into at least one cohesive porous unit; and d) curing theunit at a temperature of from about 100° F. to about 200° F. until theconcentration of water is at least about 5% by weight of composition,and the concentration of permanganate is at least about 8% by weight ofcomposition.
 23. The method of claim 22, wherein the unit is cured untilthe concentration of permanganate is between about 13 and about 25% byweight of the composition.
 24. The method of claim 22, wherein the unitis cured until the concentration of permanganate is between about 15 andabout 20% by weight of the composition.
 25. The method of claim 22,wherein the unit is cured until the concentration of permanganate isbetween about 18 and 19% by weight of the composition.
 26. The method ofclaim 22, wherein the unit is cured until the water concentration isbetween about 5% and about 25%.
 27. The method of claim 22, wherein theporous substrate comprises activated alumina, a silica gel, a zeolite, azeolite-like mineral, kaolin, an adsorbent clay, activated bauxite, or acombination thereof.
 28. The method of claim 22, further comprisingmixing the permanganate and porous substrate with a gas-evolvingmaterial, wherein the gas-evolving material is selected from a carbonatecompound, a bicarbonate compound, or a combination thereof.
 29. Themethod of claim 22, further comprising a gas-evolving material, whereinthe concentration of gas-evolving material is between about 5 and about25% by weight of the composition.
 30. The method of claim 22, whereinthe gas-evolving material is sodium bicarbonate and the porous substrateis activated alumina or a combination of activated alumina and at leastone zeolite or zeolite-like mineral.
 31. The method of claim 30, whereinthe zeolite or zeolite-like mineral is selected from amicite, analcime,pollucite, boggsite, chabazite, edingtonite, faujasite, ferrierite,gobbinsite, harmotome, phillipsite, clinoptilolite, mordenite, mesolite,natrolite, garronite, perlialite, barrerite, stilbite, thomsonite,kehoeite, pahasapaite, tiptopite, hsianghualite, lovdarite, viseite,partheite, prehnite, roggianite, apophyllite, gyrolite, maricopaite,okenite, tacharanite, tobermorite, or a combination thereof.
 32. Themethod of claim 22, wherein the concentration of the porous substratecomprises between about 40% and about 60%.
 33. The composition of claim1, wherein the solubility of the permanganate salt is greater than 6.5g/100 ml in weight, at 20° C.